Subject: [PATCH v2 88/94] KVM: arm64: Add ARMv8.4 Enhanced Nested Virt cpufeature

From: Marc Zyngier <[email-masked]>
Date: Tue, 11 Feb 2020 17:49:32 +0000

Add the detection code for the ARMv8.4-NV feature.

Signed-off-by: Marc Zyngier <[email-masked]>
---
 arch/arm/include/asm/kvm_nested.h   |  1 +
 arch/arm64/include/asm/cpucaps.h    |  3 ++-
 arch/arm64/include/asm/kvm_nested.h |  6 ++++++
 arch/arm64/kernel/cpufeature.c      | 10 ++++++++++
 4 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/arch/arm/include/asm/kvm_nested.h b/arch/arm/include/asm/kvm_nested.h
index 2b89e6fa7323..1b97863ae811 100644
--- a/arch/arm/include/asm/kvm_nested.h
+++ b/arch/arm/include/asm/kvm_nested.h
@@ -5,6 +5,7 @@
 #include <linux/kvm_host.h>
 
 static inline bool nested_virt_in_use(const struct kvm_vcpu *vcpu) { return false; }
+static inline bool enhanced_nested_virt_in_use(const struct kvm_vcpu *vcpu) { return false; }
 static inline void check_nested_vcpu_requests(struct kvm_vcpu *vcpu) {}
 
 #endif /* __ARM_KVM_NESTED_H */
diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h
index 5736650cd0fb..565e4878e301 100644
--- a/arch/arm64/include/asm/cpucaps.h
+++ b/arch/arm64/include/asm/cpucaps.h
@@ -60,7 +60,8 @@
 #define ARM64_HAS_RNG				50
 #define ARM64_HAS_NESTED_VIRT			51
 #define ARM64_HAS_ARMv8_4_TTL			52
+#define ARM64_HAS_ENHANCED_NESTED_VIRT		53
 
-#define ARM64_NCAPS				53
+#define ARM64_NCAPS				54
 
 #endif /* __ASM_CPUCAPS_H */
diff --git a/arch/arm64/include/asm/kvm_nested.h b/arch/arm64/include/asm/kvm_nested.h
index 3e3778d3cec6..284c794a10ac 100644
--- a/arch/arm64/include/asm/kvm_nested.h
+++ b/arch/arm64/include/asm/kvm_nested.h
@@ -11,6 +11,12 @@ static inline bool nested_virt_in_use(const struct kvm_vcpu *vcpu)
 		test_bit(KVM_ARM_VCPU_HAS_EL2, vcpu->arch.features);
 }
 
+static inline bool enhanced_nested_virt_in_use(const struct kvm_vcpu *vcpu)
+{
+	return cpus_have_const_cap(ARM64_HAS_ENHANCED_NESTED_VIRT) &&
+		nested_virt_in_use(vcpu);
+}
+
 extern void kvm_init_nested(struct kvm *kvm);
 extern int kvm_vcpu_init_nested(struct kvm_vcpu *vcpu);
 extern void kvm_init_nested_s2_mmu(struct kvm_s2_mmu *mmu);
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index aada8c3eff1e..546aceb70c3f 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1454,6 +1454,16 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
 		.field_pos = ID_AA64MMFR2_NV_SHIFT,
 		.min_field_value = 1,
 	},
+	{
+		.desc = "Enhanced Nested Virtualization Support",
+		.capability = ARM64_HAS_ENHANCED_NESTED_VIRT,
+		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
+		.matches = has_nested_virt_support,
+		.sys_reg = SYS_ID_AA64MMFR2_EL1,
+		.sign = FTR_UNSIGNED,
+		.field_pos = ID_AA64MMFR2_NV_SHIFT,
+		.min_field_value = 2,
+	},
 #endif	/* CONFIG_ARM64_VHE */
 	{
 		.desc = "32-bit EL0 Support",
-- 
2.20.1

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